Making a music pack is fairly easy, you could do it yourself aslong as you know how to convert the music files into WMA files. You basically put all the music into a folder called "Songs" & name the music to the exact name as the music files in the official game files based on where you want them to play, and then copy the XNB files & put them in your Songs folder aswell, and there you have your music pack.
As for if you want it to loop perfectly, that's another story.